| Acronym | Sense | Language | Topics |
|---|---|---|---|
| PI | Principal Investigator | In English | |
| PI | Proprietà Industriale | In Italian | → Industrial property |
| PI | Payload Interrogator | In English | → Astronautics |
| PI | Preliminary Investigation | In English | |
| PI | Procurement Item | In English | |
| PI | Program Introduction | In English | |
| PI | Pedologisch Instituut | In Dutch | → Education |
| PI | Primary Infertility | In English | → Reproductive biology |
| PI | Pôle Industrie | In French | → Industry, industrial policy |
| PI | Poteau Incendie | In French | → Firefighting |